Automatic train-control system



Feb, 10, 1925.

1,526,291 C. S. BUSHNELL AUTOMATIC TRAIN CONTROL SYSTEM Original Filed Septl, 1920 Patented Feb. 10, 1925.l

UNITED STATES PATENT OFFICE.

CHARLES s. .BUSHNELL .or ROCHESTER, NEW YORK, ASSIGNOE To' ,GENERAL RATE- WAY SIGNAL COMPANY, OE ROCHESTER. NEW YORK, A CORPORATION '0E NEW YORK.

AUTOMATIC TRAIN-CONTROL SYSTEM;

Application filed September 1, 1920, Serial To (/7/ :clio/i1 if 71mg/ concern:

lh it knovvu that I. CHARLES S. BUSH- NELT.. a vcitizen ot the United States, resid-` ing at lio-sinister. in the county of Monroe and State oi New York, have invented certain neu' and useful Improvements in Automatic\'l`rain-Control Systems. ot which the i'ollf.i\ving is a Specification.

This invention relates to automatic train control .systems tor railroads. and more par.- lii-ularly to an improved construction of the car-carried element of the impulse transmitting means by which the necessary controlling impulses or influences are transmitted from the track to the moving car or other vehicle.

`In ont` type ot system to which my inrenlion is more particularly applicable, the controlling impulses are transmitted by the cooperation ot' a track element with a earcarried cleincnt. acting by electroniaguetic induction' through an intervening air gap; and the track element, when in its danger or stopping condition. is in effect a magnetif.l loop. It will be evident that in a system ol this type. track raiis at crossings, crossover-s and the like. orfother masses off iron along the track,A have atendency to prcduccfthe same stopping effect as the regular trat-k elements; and the primary object o'l'- the present invention is to devise a car element ol' improvedI construction which will be influenced to a very slight degree by the track rails at crossings. crossover, andthe like. but which will be subje't to the influence ot a regular track element. Othermore limited objects and features of the invention will. appear hereinafter.

In desfribing the invention in detail reference will be made to the accompanying drawings in Which- Figure 1 shows diagrammatically one arrangement of .trackway circuits and apparatus which may be employed in connection with the car equipment embodying this in vcntion Fig.A 2, illustrates in a simplified and diagrainmatic manner one form of car equipment constructed in accordance with the inventioiutogether with the cooperating track element, the parts being shown more for the purpose ot' making it easy to understand the principles ot' the invention than With the idea of illustrating the'exact construc- No. 407,302. Renewed December 3o, 1924.

tion and arrangement of parts which would be preferably employed in practice;

Fig. 1s a plan .viewV ot thecar element; and

Fig. i is a -tragmentary plan view ot' the car element showing a modified construclion.

In the embodiment of the invention illustratetl. the transmission of the desired controlling` impulses is produced by track elements which are governed in accordance With tratiirconditions. Various arrangements of trackway. circuits suitable for this purpose may be enuiloyed,l and it should be under-` stood that the arrangement shown in Fig.

l is only typical. Referring to Fig. l, the

hattery-l and a track relay 4, the same as in ordinary block signal systems. My invention may be used With or Without the usual fixed signals, depending upon the type oi' train control apparatus; and I have illustrated such fixed signals conventionally.

without attempting to illustrate their Well known control circuits and devices.

The trackway element T of my invention in general comprises a magnetic yoke or core and associated coils, and is adapted to in- 9o tluence by electro-magnetic induction a cooperating element on a `passing vehicle. In the construction illustrated. the trackway element T comprises a U-Shaped `core or yoke 5 `provided with pole pieces 6, and hav- 95 ingcoils 'r' on its legs which are Wound and connected in series so-that the electro-motive forces generated in these coils by'ux passing through the yoke 5 are cumulativek or additive. are intended to transmit controllingT inuences or impulses to a passing train at onel or more control pointsin each block, in accordance Lwith traffic. conditions in the next block in advancej alone, or both the next block in advance and, the corresponding` block. depending upon the type of train control apparatus employed. In the track- The parts and circuits associated 75 These trackway elements T 10o way equipment shown in Fig. 1, a trackway element T is located at the entrance to each block, a short distance in the rear of the insulated joints Q, the normal direction of traffic being` from left to right, as indicated by the arrow. The coils T of each trackway clement T are connected in series in a normally closed circuit including the front contact of a line relay 8. In the arrange' ment illustrated, the controlling circuit for the line relay 8 includes a front contact of the track relay t of the corresponding block and a front contact of the track relay #t of the next block in advance. so that the coils T of the trackivay element T at the entrance to each block are in closed circuit under clear tratlic conditions, but are open-cil`- cuited when either the corresponding block or the next bloi'k in advance is occupied. The traclnvay elements T may be located crosswise of the track between the track rails (as shown in Fig. l), or lengthwise, or outside of either track rail, as preferred.

The car element li for cooperating with the track elements T comprises a yoke or core Y having three vertically disposed legs 9, 10 and 11. This yoke Y is supported in a suitable manner (not shown) from the frame of the locomotive or other vehicle, and is so positioned on this vehicle that two of its legs, as 9 and 10, which are spaced apart the same distance as the legs of the track element T, will pass directly over the pole pieces of said track element, as shown in Fig.r 2. On the middle leg 10 is a coil or winding 12, conveniently termed the primary coil; and on the other two legs 9 and 11 are similar coils 1.3 and 14, conveniently termed secondary coils. The secondary coils 13 and 14 are. wound, preferably with the same number of turns, and are connected in series, such that the electro-motive forces generated therein by a dhange in flux passing through said legs in the same direction, either up or down. will oppose each other.

ln connection with 'the system illustrated there is employed a device of the thermionic or vacuum bulb type, commonly known as an audion and conveniently referred to by that term. This audion, being well known in the art, is illustrated conventionally. Tt comprises a filament l", a grid G, and a plate P. This audion is connected up` with suitable sources of current illustrated .as batteries A, B and C, the primary and secondary coils of the car carried element L, and a control relay R, so that the operation of said relay R -is automatically determined by the controlling condi; tion of the track elements T as the vehicle successively passes them. 1t should he understood that these electrical connections may take various forms, the arrangement illustrated being merely typical.

itaaaei.

The control relay R may be of any suitable type, but T prefer to .employ a relay of a tractive type having its armature balanced about its center of gravity and biased to open by a spring; and in connection with the arrangement of circuits illustrated, T have found it desirable to use a relay having a large number of turns so as to be operable on small currents, and also having a laminated core so as to be quick acting. 1t will be evident, however, that the structural features of the relay R depend largely upon the type of audion employed, and other characteristics of the system. to control the operation of some suitable form of train control apparatus. Since this apparatus forms no part of the present invention, and may 'take any one of the various forms known in the art7 l have illustrated conventionally such a device K in the form of an electro-pneumatic valve, which may be used to vent the train pipe and apply the brakes directly, or govern the operation of some other form of speed regulating or brake controlling mechanism. This train control devlce K 1s normally energized, and is deenergized when the control relay R opens its contacts. ln the arrangement of circuits illustrated, the control relay opens its contacts only momentarily, so that it' continued operation of the train control device K is desired. some suitable means, such as a stick circuit, should be employed all in the manner which will be readily understood by those skilled in the art.

The apparatus so far described constitutes the parts of a system which l have selected to illustrate the principles and mode of operation of my improvedinvention. This system is described and claimed in other applications;

1n accordance with the present invention the two legs 91 and 11 carrying the secondary coils 13 and 1t are provided with pole pieces 15 and 16 which are elongated or extended lengthwise of the car. The pole pieces 15 and 16 may extend parallel with the track rails; or, as in the arrangement shown in Fig. 3, these pole pieces may be curved towards each other to form nearly a complete cii'cle; or, as in the arrangement shown in Fig. 4, the end portions of these pole pieces 15 A:and 16a may be overlapped With an air gapbetween.

The circuit connections between the various devices are subject to considerable modification in practice, but in the particular arrangement illustrated, the filament F of the audion is heated by the vbattery A. The grid G is connected in circuit with the secondary coils 13 and let and the battery C as follows: commencing at positive terminal of battery C, Wire 17, coil 13, Wire The control relay R is intended and in part through leakage paths.

yokes 9 and A5.

battery Bi) wires` 20, and 21, relay R, wire 22, plate and thence through the audion .to the filament F and battery C' back to the other terminal ofbattery B. The primary coil 12 is normally energized by a. circuit as follows: `commencing at batter B, wires 20 and 23, train control device i, wire2-i, contact finger 25 of relay R, wires 26 and 27, coil 12,\wire 28, adjustable resistance 29, wire 30 and battery C backy to the other terminal `of the battery B. `In

order to protect the relay contacts from inju "or deterioration bythe arcs accompanying the breaking of the inductive circuit through the coil 12, a resistance 31 is preferably connected across these relay contacts. e y

Operatz'onNormally the battery C produces a positive potential upon. the grid Gr with respect to thenegative end or average potential of the filament F, and thus permits current to` flow in the plate circuit through thel relay R, on account of the well.

known characteristics 'of the faudion. The relay R being energized current flows through the primary coil 12 and produces magneto-motive force tendingto send flux through the yoke 9. When the car is traveling between track elements T, this iiux passes in `part through the legs of the yoke 9 The reluctance of the artial magnetic ycircuit afforded by the `yo e 9 is relatively high.`

Assume nowthat the car passes overa track element *T which has its coils l7 open-circuited, corresponding to dangerous traflic conditions ahead. A track element T is this conditionpresents in effect a dead mag- 'netic loop for the two'lefthand legs of the` yoke 9 on the passing car, and it will be.

evident that as the car passes such magnetic loop, the reluctance of the partial magnetic circuitof the yoke 9 through the primary coil 12 and the secondary coil 13 is greatly changed, being decreased from the normal to a minimum and then back to normal as the car passes the track element. This change iu reluctance in turn changes the amount of ilux` passing through the coils `12--13. the flux normally'. passing through the leakage paths being divertedto the path of lower reluctance through the iron of the As the iux through the coil 13 is increased, an electro-motive force i's induced in said coil, which inaccordance` with well known-laws, `tends to produce a current making amagneto-motive forcelopposing this change of'lux; and the wlndlngs `are so arranged and connected that this induced electro-motive forcelopposes the voltage of the battery C and reduces the potential on the gridv G. The normal potential on the grid G being thus lowered, the current normally iiowing in the ,plate circuit through the control relayA R is likewise decreased, and" the parts are so proportioned and adjusted` that the current through the relay Ris reduced in this way below the value of current vrequired to hold its contacts closed. Consequently, the contacts of the relayl R open and deenergizethe' train control device K. `Under clear `traffic conditions,- the coils 7 of the track element T are included in' a closed circuit of low re- Sistance; and when the car carried element Lv passes over a track element in this clear condition, the ycar equipment is not influenced, atleast suiiciently to cause operation of' the relay R. This is attributed to the action of the coils 7 which, it "is believed, opposes or chokes back the-passage of flux throughthe yoke 5 because `of the current induced in`said coils,` It is found in practice that the numberof turns on the coils 7, thellength of the magnetic circuits, and the like, may be proportioned so that there is' little change in the flux through-the secondary coil 13 as it passes the track element T having its coils in cldsed circuit.

It will be` evident that track rails or similarlm'asses of iron along the track will tend to 4cause operation di the control relay R in the same way as a track element T in'the danger or stopping condition; and to neutralize this objectionable interference, more particularly vin the case of track rails, the additional leg and secondary coil 14 are employed. `If both of the outer legs of the yoke Y pass over a magnetic body, as a track rail, substantially the same change in flux takes place through the coils 13 and 14; e

and since these coils are wound oppositely,

the electro-motive Jforces induced therein are to the'track rails on which the car is traveling, as, for example, the points of a crossover. \In such cases thetra'ck rail will approach or lrecede from the legs 9 and 10, before or after coming under the leg 11, with the result that the, change of flux in :the coils V13I and 14 does'inot take place simultaneously and tof/,the same extent, thereby destroying the exacttbalancing or neutralizing action of the secondary coil 14. This is assuming that the legs 9, 10 and 11 have short or square poleypieces.

In accordance with the present invention, however, the elongated pole pieces 15 and 16 act as collectors for the legs 9 and 11, and cause a change of flux in both of the secondary coils 13 and y14 substantially simultaneously and to the same extent. as the car passes over an inclined rail. There are in yeffect two partial magnetic circuits in the car element L, oneI through the legs 9 and l10 and coils 12 and 13, and thc other through the legs 10 and 11. and coils l2 and 14. ,In passing over a track element T, in the stopping condition, the partial magnetic circuit through coils 12 and 13 is completed through the yoke 5 of said track element and the intervening air-gaps, while the other magnetic circuit through the secondary coil 14 is not materially affected. In passiugfover an inclined track rail` both magnetic circuits are affected through the elongated pole pieces 15 and 1G; and although the length of the path through the iron of these pole p-ieccs may not be the same, the change in :reluctance of said partial magnetic circuits is practically the same. In this connection, it should be remembered that the pole pieces of the yoke Y are separated from the track rails by an air gap which must be at least an inch or two, on account of the clearances demanded by practical railroad conditions. Such an air gap provides, therefore, the greater part of the reluctance of the magnetic rcircuit through the yoke Y and the track rail; and consequently the effect of some additional iron path through the elongated pole pieces 15 and 16 is practically negligible.

The arrangement of elongated polepieces does not seriously detract from the effect produced by an active track element T. I attribute this to the fact that a track element produces its maximum influence While passing directly under the legs 9 and 10, and at such time said track element is not in position to aect the neutralizing secondary coil 14 directly, or through its elongated pole piece 16.

While I have described my invention in connection with ay system of the specific type embodying an audion` the invention is not limited to this type of system and I desire to have it understood that the specific embodiment of my invention. shown and dcscribed is merely illustrative, and does not exhaust the adaptations and modifications of means and functions thereof constituting the invention.

What I claim as new and desire to secure h v Letters Patent of the United States is 1. In a systemof automatic train control ot the type in which controlling impulses are transmitted from the track to moving ars through an intervening air gap by the. cooperation of a car element with a track element which acts as a magnetic body when 1n the stopping condition, a car element comprising a three-legged yoke, `two of said legs having elongated pole pieces, oppositely wound coils on said two legs, and electroresponsive means having an operating circuit connected to said coils in series.

2.v In an automatic train control system of the type specified in claim 1. a car element comprising a source of magneto-motiveforce, two oppositely wound coils in circuit therewith. electro-responsive means having an operating cirruit including said coils in series. and magnetic members extending in a horizontal plane and acting as collectors for said coils.

In an automatic train control system of the type specified in claim 1, a car element arranged to provide two magnetic circuits. a source of magneto-motiveforce for said magnetic circuits, means operated when the reluctance of only one but not both of said circuits is changed, and magnetic members extending horizontally and acting as collectors for said circuits.

4. In an automatic train control system of the type specified in claim 1. a car element,

comprising a three-legged yoke, the outside VAlegs of said yoke having horizontally dis- `posed pole pieces curving toward eachother, and means operated when the reluctance of the magnetic circuit through one of the outlside legs is changed.

5. A car element for automatic train control systems comprising a yoke having three legs, the two outside legs having elongated pole pieces curving toward each other and acting as collectors.

6. A car element for automatic traincontrol systems comprising a three-leg ed yoke provided with coils and having tve ongated pole pieces on the outside legs curved toward each other in the same plane.

7. A car-carried train control apparatus comprising, a three-legged yoke, two of said legs having horizontally extended pole pieces, oppositely wound coils on said two legs connected to the grid circuit of a thermionic amplifier, and train control mechanism controlled by said amplifier.

8. A car-carried train control mechanism comprising, a three-legged yoke, two of said legs having elongated pole pieces, oppositely wound coils on said two legs for governing a. thermionic amplifier. and train control means controlled by said amplifier.

9. A car-carried impulse 4device for automatic train control systems comprising, a plurality of partial magnetic circuits, and means associated with said magnetic circuits for changing the reluctance of each of said circuits simultaneously when said device passes over a bar of magnetic material of sufficient length to span said device, disposed atany angle to the direction of the motion.

10. A car-carried element for automatic train control systems comprising a yoke with two legs, each of said legs terminating in horizontally disposed elongated pole pieces curved toward each other and adapted to be bridged by an elongated member on the track at substantially any angle with respect to the legs.

11. A car-carried element for automatic traincontrol systems comprising, a threelegged yoke, two of said legs terminating in pole pieces extending horizontally substantially around the third leg.

12. A car-carried element for automatic train control systems comprising, a threelegged yoke, two of said legs terminating in pole pieces magnetically separated and substantially surrounding the other leg.

13. In a train control system, .a car-carried influence receiving element comprising, two windings, a sourceot magneto-motive torce for said windings, and horizontally extendedunagnetic members associated with said windings and cooperating with a rail at substantially any angle to the runniaf.s rails to direct flux simultaneously througn both windings during movement of the element over such rail, and a track element adapted when in the stopping condition to directk flux from said source through one of said windings only.

14. In a train control system, a car-carried influence receiving element comprising, two windings and a core for said windingshaving pole pieces extended to come simultaneously over a railat substantially any angle to the running railsduring movementof the element over such rail.

15. In a train control system, the combination with a non-magnetized track element `extending -partway across the track between the rails, a car-carried receiving `element comprisingy two partial magnetic circuits, said track element acting to complete one of sald magnetic clrcuits but not the other, the .car-carried element having horizontally extended magnetic members adapted to cooperate with a rail at substantially any angle to the track rails land form a path for flux through both of said magnetic circuits during its movement over such rail. l

16. In a train control system, the combination with a car-carried element having a core with three legs, one of said legs having a pole piece extending horizontally tar enough to come over a rail at any angle at the time said rail comes under one of the other legs, and a track element of magnetic'material bridging the other two -legs onl 1%. In. a train control system, the combination with a track element comprising, a U-shaped magnetic core, and a car-earned element having three legs, two of said Vlegs leg.

passing-.over the ends of the core of the track element, the third leg having a pole piece extending horizontally far-enough to come over a rail at any angle to the trackway at the time said rail comes under one of the other legs.

18. In a train control system, the combination with yoke disposed crosswisc of the car and hav-` ing horizontal pole pieces extended for a substantial distance lengthwise of the car, and a track element including a U-shaped magnetic core bridging two legs only on said yoke.

19. In a train control system, the combination with a car-carried influence receiving element comprising, two partial magnetic circuits and a source of magnetomot-ive torce in each. circuit, electro-responsive means operated by a changing of fluxin one ot said circuits, said means not responding to simultaneous change of flux in both of said circuits, said car element haring horizontally extended magnetic members arranged to cooperate with a rail at substantially anyV angle to the track rails and to simultaneously change luxin both of said magnetic circuits as the element passes such rail, and a track element `tor causing a change of flux `in one ot' said magnetic circuitsbut not the other.

20. A car-carried iniiuencc receiving element comprising, a three-legged yoke disposed crosswise of the car, two legs ot said yoke `having horizontally vextended lpole pieces arranged to be both over a track rail at substantially any angle to the running rails duringv movement of the third leg over said track rail.

Q1. A car-carried inuence receiving element comprising, a core having three legs. two of said legs having pole pieces extended horizontally on opposite sides of the third 22. In a train control system, the combination with a car-carried element comprising, a core having three legs, two ot' said legs having horizontally extended pole pieces, and a track element bridging only one of said two legs and the third leg.

23. A car-carried influence receiving element for cooperation Awith a track element having a non-magnetized U-shaped core, comprising two-partial magnetic circuits,

cach terminating in elongated pole pieces extended horizontally lengthwise ot' the car.

Q4. A car-carried influence element for automatic train control s \'sten1,comprisi1ig a` primary coil, two oppositely wound sec ondary coilsl connected inseries, electro-responsive mea-ns Vlgoverned by potential changes in said secondary coils, and magnetic members extended horizontally lengthwise of the car and arranged to form a path for flux from the primary coil through both a car-carried three-legged f secondary coils sinniltaneonsly during movement of the ear over a rail disposed at substantially any angle to the car.

car-carried element Ator train control system, comprising a prin'iary eoil and a core therefor7 Said core extendingcross \vi. c ott' the ear, and horizontall)v disposed elongated pole pieces extended forwardly and rearwardly with respect'. to the car.

26. A car-carried element for train control system comprising, a core extending transversely of the ear and having three downwardly extending legs, t\\'o ol the legs havingr arcuate pole pieces disposed salutantially in the same horizontal plane and rail)- stantially surrounding the third leg hat magnetically separated.

27. In a train control q'stem train control mechanism on a vehicle`r an inllnenee receiving element on the vehiele including a primary coil, an energizing eircnit lor the eoil controlling said train eontrol mech anibm, electro-responsive mean`l lolgoverning the operation ol' [he train eontrol meehanism, oppositely wound feeondar)Y coils eonnected in series l'or j foverningl they electr responSive means7 and elongated pole pieces asociated \\ith.k1e omlar vcoil# and dispoaed horizontally on opposite sides ot' the pri mary coil.

28. A car-carried influence receiving element for train control Systems, and electroresponsive means associated therewith, Said electro-resaponsive means heing operated when said ear-carried element cooperates with a track clement constituting a partial magnetic eireiiit when in the active stopping condition, lSaid car element heing provided with horizontally disponed magnetic niemhers extended lengthwise of the vehicle and adapted to he hridged hv a track rail at snhstantiallvy an}v angle.

2t). ear-carried element for train control systems7 comprising a three-legged volte, a primar)Y eoil on one leg, oppositel)v vvound neeondarv eoil I eonneeted in Series on they otherl trio legs, said other tvvo legs having extended pole pieren adapted to he hridged h v a rail at' snhstantiallv any angl@ tothe tract; aih a.` it eomes opposite the legon which the prinn-.r eoil is earried.

lll. ral' i-le:.ieiil loi' :iiitolilatie train eolitrol jf te1nreompri ing. a threelegged yoke having two ol' il h'g l provided \\'it.h pole pieee extending in a horizontal plane with their ends overlapped and lirronmlingr the third leg.

ln iestinioirv whereol l have allixed in v .\ignatnre. 

